The present invention relates to a semiconductor integrated circuit technology and a technology effective for application to a reduction in DC offset of each of multistage-connected amplifiers, e.g., a technology effective for application to a direct conversion type signal processing LSI (Large Scale Integration) for processing transmit and receive signals used in a cellular telephone.
A system called a “superheterodyne system” has heretofore been known for a radio communication LSI for processing transmit and receive signals used in a cellular phone. Such a configuration as shown in FIG. 10 by way of example is considered as a reception-system circuit based on the superheterodyne system. Namely, as illustrated in FIG. 10, the reception-system circuit comprises a bandwidth limiting filter (FLT) 111 comprising a SAW filter which eliminates an unnecessary wave from a signal received by an antenna AT, a low noise amplifier (LNA) 112 which amplifies the signal having passed through the filter 111, a mixer (MIX) 113 which combines the amplified received signal with a local oscillation signal generated from an oscillation-system circuit 130 and thereby down-converts it to a signal having an intermediate frequency, a bandpass filter (BPF) 114 which allows a signal having a frequency equivalent to the difference in frequency between the received signal and the local oscillation signal to pass therethrough, a gain-controllable programmable gain amplifier (PGA) 115 which amplifies a signal to a desired level, a demodulator (DeMOD) 116 which demodulates a signal adjusted to a desired width into a baseband signal (I/Q) having a voice frequency, etc.